On Sat, Jul 31, 2021 at 9:56 AM Roger Sayle <ro...@nextmovesoftware.com> wrote: > > > Many thanks again to Jakub Jelinek for a speedy fix for PR 101642. > Interestingly, that test case "bswap16(x) ? : x" also reveals a > missed optimization opportunity. The resulting "x ? bswap(x) : 0" > can be further simplified to just bswap(x). > > Conveniently, tree-ssa-phiopt.c already recognizes/optimizes the > related "x ? popcount(x) : 0", so this patch simply makes that > transformation make general, additionally handling bswap, parity, > ffs and clrsb. All of the required infrastructure is already > present thanks to Jakub previously adding support for clz/ctz. > To reflect this generalization, the name of the function is changed > from cond_removal_in_popcount_clz_ctz_pattern to the hopefully > equally descriptive cond_removal_in_builtin_zero_pattern. > > The following patch has been tested on x86_64-pc-linux-gnu with a > "make bootstrap" and "make -k check" with no new failures. > > Ok for mainline?
OK. Thanks, Richard. > > 2021-07-31 Roger Sayle <ro...@nextmovesoftware.com> > > gcc/ChangeLog > * tree-ssa-phiopt.c (cond_removal_in_builtin_zero_pattern): > Renamed from cond_removal_in_popcount_clz_ctz_pattern. > Add support for BSWAP, FFS, PARITY and CLRSB builtins. > (tree_ssa_phiop_worker): Update call to function above. > > gcc/testuite/ChangeLog > * gcc.dg/tree-ssa/phi-opt-25.c: New test case. > > > Roger > -- > Roger Sayle > NextMove Software > Cambridge, UK >
